Heat-assisted magnetic write head, head gimbals assembly, head arm assembly, and magnetic disk device

ABSTRACT

A heat-assisted magnetic write head includes a magnetic pole having an end surface exposed at an air bearing surface, a waveguide extending toward the air bearing surface to propagate light, and a plasmon generator provided between the magnetic pole and the waveguide, and generating near-field light from the air bearing surface, based on the light propagated through the waveguide. The plasmon generator has an end portion exposed at the air bearing surface or located in close proximity to the air bearing surface, the end portion having a minimum thickness in a region close to the waveguide.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat-assisted magnetic write headused in a heat-assisted magnetic recording in which near-field light isirradiated to lower a coercivity of a magnetic recording medium so as torecord information, and a head gimbals assembly, a head arm assembly,and a magnetic disk device mounted with the heat-assisted magnetic writehead.

2. Description of Related Art

A magnetic disk device in the related art is used for writing andreading magnetic information (hereinafter, simply referred to asinformation). The magnetic disk device is provided with, in the housingthereof, a magnetic disk in which information is stored, and a magneticread write head which records information into the magnetic disk andreproduces information stored in the magnetic disk. The magnetic disk issupported by a rotary shaft of a spindle motor, which is fixed to thehousing, and rotates around the rotary shaft. On the other hand, themagnetic read write head is formed on a side surface of a magnetic headslider provided on one end of a suspension, and the magnetic read writehead includes a magnetic recording element and a magnetic reproducingelement which have an air bearing surface (ABS) facing the magneticdisk. In particular, as the magnetic reproducing element, amagneto-resistive (MR) element exhibiting magneto resistive effect isgenerally used. The other end of the suspension is attached to an edgeof an arm which is rotatably supported by a fixed shaft installedupright in the housing.

When the magnetic disk device is not operated, namely, when the magneticdisk does not rotate, the magnetic read write head is not located overthe magnetic disk and is pulled off to the position away from themagnetic disk (unload state). When the magnetic disk device is drivenand the magnetic disk starts to rotate, the magnetic read write head ischanged to a state where the magnetic read write head is located at apredetermined position over the magnetic disk together with thesuspension (load state). When the rotation number of the magnetic diskreaches a predetermined number, the magnetic head slider is stabilizedin a state of slightly floating over the surface of the magnetic diskdue to the balance of positive pressure and negative pressure. Thus, theinformation is accurately recorded and reproduced.

In recent years, with a progress in higher recording density (highercapacity) of the magnetic disk, an improvement in performance of themagnetic read write head and the magnetic disk has been demanded. Themagnetic disk is a discontinuous medium including collected magneticmicroparticles, and each magnetic microparicle has a single-domainstructure. In the magnetic disk, one recording bit is configured by aplurality of magnetic microparticles. Since the asperity of a boundarybetween adjacent recording bits is necessary to be small in order toincrease the recording density, the magnetic microparticles need to bemade small. However, if the magnetic microparticles are small in size,thermal stability of the magnetization of the magnetic micorparticles islowered with decreasing the volume of the magnetic maicroparticles. Tosolve the difficulty, it is effective to increase anisotropic energy ofthe magnetic microparticles. However, increasing the anisotropic energyof the magnetic microparticles leads to increase in the coercivity ofthe magnetic disk. As a result, difficulty occurs in the informationrecording using the existing magnetic head.

As a method to solve the above-described difficulty, a so-calledheat-assisted magnetic recording has been proposed. In the method, amagnetic recording medium with large coercivity is used. When recordinginformation, heat is applied together with the magnetic field to aportion where the information is recorded out of the magnetic recordingmedium to increase the temperature and to lower the coercivity, therebyrecording the information. Hereinafter, the magnetic head used for theheat-assisted magnetic recording is referred to as a heat-assistedmagnetic write head.

In the heat-assisted magnetic recording, near-field light is generallyused for applying heat to the magnetic recording medium. As a method ofgenerating near-field light, a method using a near-field light probethat is a metal strip generating near-field light from a plasmon whichis excited by light, that is, so-called plasmon generator is generallyknown. However, it is known that the plasmon generator which generatesnear-field light by direct irradiation of light converts the irradiatedlight into near-field light with extremely low efficiency. A large partof energy of light irradiated to the plasmon generator is reflected bythe surface of the plasmon generator or converted into heat energy to beabsorbed to the plasmon generator. The size of the plasmon generator isset smaller than the wavelength of light so that the volume of theplasmon generator is small. Therefore, in the plasmon generator,increase of temperature involved with the absorption of heat energybecomes extremely large.

In the heat-assisted magnetic recording, from the viewpoint of theefficiency and the precision, on the surface facing the medium, thegeneration position of the recording magnetic field and the generationposition of the near-field light are desirably approached as much aspossible. For example, U.S. Patent Application Publication No.2007/139818 specification discloses a magnetic head in which anear-field light generation section that generates near-field light inresponse to irradiation of laser light and an end portion of a mainmagnetic-pole layer are arranged to be laid over with a dielectric layerin between or directly with each other on a surface facing the medium.In addition, U.S. Patent Application Publication No. 2009/168220specification discloses a magnetic head in which at least a part of amagnetic pole is arranged between first and second near-field lightgeneration sections that respectively generate near-field light inresponse to irradiation of laser light. However, if a magnetic polegenerating recording magnetic field is arranged near a plasmon generatorgenerating near-field light, the main magnetic pole is heated withincreasing the temperature of the plasmon generator. As a result,depending on the humidity condition of the atmosphere, there is apossibility that the main magnetic pole is corroded by moisture in theair.

Consequently, it is desirable to suppress corrosion due to the increaseof the temperature of the main magnetic pole from occurring, and tosecure long-term reliability while maintaining the recording property.

SUMMARY OF THE INVENTION

A heat-assisted magnetic write head according to an embodiment of theinvention includes: a magnetic pole having an end surface exposed at anair bearing surface; a waveguide extending toward the air bearingsurface to propagate light; and a plasmon generator provided between themagnetic pole and the waveguide, and generating near-field light fromthe air bearing surface, based on the light propagated through thewaveguide. The plasmon generator an end portion exposed at the airbearing surface or located in close proximity to the air bearingsurface, the end portion having a minimum thickness in a region close tothe waveguide.

A head gimbals assembly, a head arm assembly, and a magnetic disk deviceaccording to an embodiment of the invention include the above-describedheat-assisted magnetic write head.

In the heat-assisted magnetic write head according to an embodiment ofthe invention, the plasmon generator has the end portion having aminimum thickness in a region close to the waveguide. Therefore, on theair bearing surface, the magnetic pole and the generating position ofthe near-field light are further approached. On the other hand, thethickness of a portion other than the portion located close to thewaveguide is increased to improve the efficiency of heat dissipation ofthe plasmon generator. Therefore, compared to the case where the endportion of the plasmon generator has a certain thickness, while theefficiency and precision of the heat-assisted magnetic recording areimproved, increase of temperature of the magnetic pole and in thevicinity thereof is suppressed, and therefore the corrosion of themagnetic pole and defect in the configuration near the magnetic pole areless likely to occur. As a result, while securing the long-timereliability, the recording operation may be achieved with increasedefficiency and stability.

In the heat-assisted magnetic write head according to an embodiment ofthe invention, the end portion of the plasmon generator preferablyincludes, for example, a V-shaped mid-portion including a pointed edgeprojected toward the waveguide, and a couple of wing portions facing toeach other with the mid-portion in between in a direction across writetracks. The magnetic pole is preferably provided to be in contact withthe mid-portion of the plasmon generator. Further, the magnetic polepreferably has a width smaller than that of the waveguide and of themid-portion in the direction across write tracks. When theabove-described configuration is applied, distribution of recordingmagnetic field emitted from the magnetic pole has a steeper shape. As aresult, the maximum intensity of the recording magnetic field necessaryfor information recording is further increased. Moreover, themid-portion has a minimum thickness at the pointed edge, and thethickness is desirably increased with increasing distance from thepointed edge in the direction across tracks. With such a configuration,the maximum intensity of the recording magnetic field emitted from themagnetic pole is further increased, edge peaks (peaks of recordingmagnetic field of the magnetic pole in the vicinity of both ends in thedirection across tracks) are less likely to occur because an interfacebetween the magnetic pole and the plasmon generator is a smoothcurved-surface, and therefore the magnetic flux is suppressed fromleaking into the adjacent tracks.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a configuration of a magneticdisk device provided with a magnetic read write head according to anembodiment of the invention.

FIG. 2 is a perspective view illustrating a configuration of a slider inthe magnetic disk device illustrated in FIG. 1.

FIG. 3 is a plane view illustrating a configuration of a main part ofthe magnetic read write head illustrated in FIG. 2, viewed from an arrowIII direction.

FIG. 4 is a sectional view illustrating a configuration of the magneticread write head illustrated in FIG. 3, viewed from the arrow directionalong a IV-IV line.

FIG. 5 is a plane view illustrating a configuration of an end surfaceexposed at an air bearing surface of a main part of the magnetic readwrite head.

FIG. 6 is an exploded perspective view illustrating a configuration of amain part of the magnetic read write head.

FIG. 7 is another perspective view illustrating a configuration of themain part of the magnetic read write head.

FIG. 8 is a sectional view illustrating a configuration of a sectionsurface, which is orthogonal to the air bearing surface, of the mainpart of the magnetic read write head.

FIG. 9 is a plane view illustrating the main part of the magnetic readwrite head.

FIG. 10 is a sectional view for describing a manufacturing process ofthe main part of the magnetic read write head.

FIG. 11 is a sectional view for describing a process following theprocess of FIG. 10.

FIG. 12 is a sectional view for describing a process following theprocess of FIG. 11.

FIG. 13 is a sectional view for describing a process following theprocess of FIG. 12.

FIG. 14 is a sectional view for describing a process following theprocess of FIG. 13.

FIG. 15 is a sectional view for describing a process following theprocess of FIG. 14.

FIG. 16 is a sectional view for describing a process following theprocess of FIG. 15.

FIG. 17 is a block diagram illustrating a circuit configuration of themagnetic disk device illustrated in FIG. 1.

FIG. 18 is an explanatory diagram for describing an operation of themagnetic read write head.

FIG. 19 is a plane view illustrating a configuration of an end surfaceexposed at the air bearing surface, of a magnetic read write headcorresponding to Example 2.

FIG. 20 is a plane view illustrating a configuration of an end surfaceexposed at the air bearing surface, of a magnetic read write headcorresponding to Example 3.

FIG. 21A is a characteristic diagram illustrating intensity distributionof recording magnetic field in a direction across write tracks inExample 1.

FIG. 21B is a characteristic diagram illustrating intensity distributionof recording magnetic field in a direction across write tracks inExample 2.

FIG. 21C is a characteristic diagram illustrating intensity distributionof recording magnetic field in a direction across write tracks inExample 3.

FIG. 22 is a characteristic diagram illustrating intensity distributionof recording magnetic field on a section surface including pointed edgealong a write track direction.

FIG. 23 is a plane view illustrating a configuration of an end surfaceexposed at the air bearing surface, of a magnetic read write head inModification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the invention will be describedin detail with reference to drawings.

[Configuration of Magnetic Disk Device]

First, referring to FIG. 1 and FIG. 2, a configuration of a magneticdisk device will be described below as an embodiment of the invention.

FIG. 1 is a perspective view illustrating an internal configuration ofthe magnetic disk device as the embodiment. The magnetic disk deviceadopts load/unload system as a driving system, and includes, inside ofthe hausing 1, a magnetic disk 2 as a magnetic recording medium in whichinformation is to be recorded, and a head arm assembly (HAA) 3 forwriting information in the magnetic disk 2 and reading the information.The HAA 3 is provided with a head gimbals assembly (HGA) 4, an arm 5supporting a base of the HGA 4, and a driving section 6 as a powersource for rotating the arm 5. The HGA 4 includes a magnetic head slider(hereinafter, simply referred to as a slider) 4A having a side surfaceprovided with a magnetic read write head (described later) according tothe embodiment, and a suspension 4B having an end portion provided withthe slider 4A. The arm 5 supports the other end of the suspension 4B (anend portion opposite to the end portion provided with the slider 4A).The arm 5 is configured so as to be rotatable around a fixed shaft 7fixed to the housing 1 through a bearing 8. The driving section 6 isconfigured by, for example, a voice coil motor. The magnetic disk devicehas a plurality (four in FIG. 1) of magnetic disks 2, and the slider 4Ais disposed corresponding to recording surfaces (a front surface and arear surface) of each of the magnetic disks 2. Each slider 4A is capableof moving in a direction crossing a write track, that is, in a directionacross tracks (in X-axis direction) in a plane parallel to the recordingsurface 2S of each magnetic disk 2. On the other hand, the magnetic disk2 is configured to rotate around a spindle motor 9 fixed to the housing1 in the rotation direction 2R substantially orthogonal to the X-axisdirection. With the rotation of the magnetic disk 2 and the movement ofthe slider 4A, information is written into the magnetic disk 2 or storedinformation is read out. Further, the magnetic disk device has a controlcircuit (described later) which controls a write operation and a readoperation of a magnetic read write head 10, and controls an emissionoperation of a laser diode as a light source which generates laser lightused for heat-assisted magnetic recording which will be described later.

FIG. 2 illustrates a configuration of the slider 4A illustrated inFIG. 1. The slider 4A has, for example, a block-shaped substrate 11 madeof Al₂O₃.TiC (AlTiC). The substrate 11 is substantially formed as ahexahedron, for example, and one surface thereof corresponds to an ABS11S disposed oppositely and proximally to the recording surface 2S ofthe magnetic disk 2. When the magnetic disk device is not driven,namely, when the spindle motor 9 is stopped and the magnetic disk 2 doesnot rotate, the slider 4A is pulled off to the position away from themagnetic disk 2 (unload state), in order to prevent contact of the ABS11S and the recording surface 2S. In contrast, when the magnetic diskdevice is initiated, the magnetic disk 2 starts to rotate at a highspeed by the spindle motor 9, and the arm 5 is rotated around the fixedshaft 7 by the driving section 6. Therefore, the slider 4A moves abovethe front surface of the magnetic disk 2, and is in a load state. Therotation of the magnetic disk 2 at a high speed leads to air flowbetween the recording surface 2S and the ABS 11S, and lift force causedby the air flow leads to a state where the slider 4A floats to maintaina certain distance (magnetic spacing) MS (in FIG. 5 described later)along a direction (Y-axis direction) orthogonal to the recording surface2S. On the element forming surface 11A that is one side surfaceorthogonal to the ABS 11S, the magnetic read write head 10 is provided.Incidentally, on a surface 11B opposite to the ABS 11S of the substrate11, a light source unit 50 is provided in the vicinity of the magneticread write head 10.

[Detailed Configuration of Magnetic Read Write Head]

Next, the magnetic read write head 10 will be described in more detailwith reference to FIGS. 3 to 5.

FIG. 3 is a plane view of the magnetic read write head 10 viewed from adirection of an arrow III illustrated in FIG. 2, FIG. 4 is a sectionalview illustrating a configuration thereof in an arrow direction along aIV-IV line illustrated in FIG. 3, and FIG. 5 illustrates a part of anend surface exposed at the ABS 11S in enlarged manner. The magnetic readwrite head 10 has a stacked structure including an insulating layer 13,a read head section 14, a write head section 16, and a protective layer17 which are stacked in order on the substrate 11. Each of the read headsection 14 and the write head section 16 has an end surface exposed atthe ABS 11S.

The read head section 14 performs a read process using magneto-resistiveeffect (MR). The read head section 14 is configured by stacking, forexample, a lower shield layer 21, an MR element 22, and an upper shieldlayer 23 in order on the insulating layer 13.

The lower shield layer 21 and the upper shield layer 23 are respectivelyformed of a soft magnetic metal material such as NiFe (nickel ironalloy), and are disposed oppositely to sandwich the MR element 22 in thestacking direction (in Z-axis direction). As a result, the lower shieldlayer 21 and the upper shield layer 23 exhibit a function to protect theMR element 22 from the influence of unnecessary magnetic field.

One end surface of the MR element 22 is exposed at the ABS 11S, and theother surfaces thereof are in contact with an insulating layer 24filling a space between the lower shield layer 21 and the upper shieldlayer 23. The insulating layer 24 is formed of an insulating materialsuch as Al₂O₃ (aluminum oxide), AlN (aluminum nitride), SiO₂ (silicondioxide), or DLC (diamond-like carbon).

The MR element 22 functions as a sensor for reading magnetic informationrecorded in the magnetic disk 2. Note that in the embodiment, in adirection (Y-axis direction) orthogonal to the ABS 11S, a directiontoward ABS 11S using the MR element 22 as a base or a position near theABS 11S is called “front side”. A direction toward opposite side to theABS 11S using the MR element 22 as a base or a position away from theABS 11S is called “back side”. The MR element 22 is a CPP (currentperpendicular to plane)—GMR (giant magnetoresistive) element whose sensecurrent flows inside thereof in a stacking direction. The lower shieldlayer 21 and the upper shield layer 23 each function as an electrode tosupply the sense current to the MR element 22.

In the read head section 14 with such a structure, a magnetizationdirection of a free layer (not illustrated) included in the MR element22 changes depending on a signal magnetic field from the magnetic disk2. Thus, the magnetization direction of the free layer shows a changerelative to a magnetization direction of a pinned layer (notillustrated) also included in the MR element 22. When the sense currentis allowed to flow through the MR element 22, the relative change in themagnetization direction appears as the change of the electricresistance. Therefore, the read head section 14 detects the signalmagnetic field with use of the change to read the magnetic information.

On the read head section 14, an insulating layer 25, an intermediateshield layer 26, and an insulating layer 27 are stacked in order. Theintermediate shield layer 26 functions to prevent the MR element 22 frombeing affected by a magnetic field which is generated in the write headsection 16, and formed of, for example, a soft magnetic metal materialsuch as NiFe. The insulating layers 25 and 27 are formed of the similarmaterial to the insulating layer 24.

The write head section 16 is a vertical magnetic write head performing arecording process of heat-assisted magnetic recording system. The writehead section 16 has, for example, a lower yoke layer 28, a leadingshield 29 and a connecting layer 30, a clad layer 31, a waveguide 32,and a clad layer 33 in order on the insulating layer 27. Incidentally,the leading shield 29 may be omitted from the structure.

The lower yoke layer 28, the leading shield 29 and the connecting layer30 each are formed of a soft magnetic metal material such as NiFe. Theleading shield 29 is located at the frontmost end of the upper surfaceof the lower yoke layer 28 so that one end surface of the leading shield29 is exposed at the ABS 11S. The connecting layer 30 is locatedbackward of the leading shield 29 on the upper surface of the lower yokelayer 28. The clad layer 31 is made of a dielectric material having arefractive index lower than that of the waveguide 32, and is provided tocover the lower yoke layer 28, the leading shield 29 and the connectinglayer 30. The waveguide 32 provided on the clad layer 31 extends in adirection (Y-axis direction) orthogonal to the ABS 11S, one end surfaceof the waveguide 32 is exposed at the ABS 11S, and the other end surfaceis exposed at the backward thereof. Note that the front end surface ofthe waveguide 32 may be located at a receded position from the ABS 11Swithout being exposed at the ABS 11S. The waveguide 32 is formed of adielectric material which allows laser light to pass through. The cladlayers 31 and 33 are configured by a dielectric material having arefractive index lower than that of the waveguide 32, with respect tothe laser light propagating through the waveguide 32. For example, whenthe waveguide 32 is formed of Al₂O₃ (aluminum oxide), the clad layers 31and 33 may be formed of SiO₂ (silicon dioxide). Alternatively, thewaveguide 32 is configured by Ta₂O₅ (tantalum oxide), and the cladlayers 31 and 33 may be formed of Al₂O₃.

The write head section 16 further includes a plasmon generator 34provided above the front end of the waveguide 32 through the clad layer33, and a magnetic pole 35 provided to be in contact with the uppersurface of the plasmon generator 34. The plasmon generator 34 and themagnetic pole 35 are arranged so that one end surface of each of theplasmon generator 34 and the magnetic pole 35 is exposed at the ABS 11S.The magnetic pole 35 is configured by stacking a first layer 351 and asecond layer 352 in order on the plasmon generator 34. Both the firstlayer 351 and the second layer 352 are configured of a magnetic materialwith high saturation flux density such as iron-based alloy. Examples ofthe iron-based alloy include FeCo (iron cobalt alloy), FeNi (iron nickelalloy), and FeCoNi (iron cobalt nickel alloy). The plasmon generator 34generates near-field light NF (described later) from the ABS 11S, basedon the laser light which is propagated through the waveguide 32. Themagnetic pole 35 stores therein magnetic flux generated in a coil 41(described later), releases the magnetic flux from the ABS 11S, therebygenerating a recording magnetic field for writing magnetic informationinto the magnetic disk 2. The plasmon generator 34 and the first layer351 are embedded in the clad layer 33. The detail of the configurations,functions and the like of the plasmon generator 34 and the magnetic pole35 will be described later.

The write head section 16 further includes a connecting layer 36embedded in the clad layer 33 at the backward of the plasmon generator34 and the magnetic pole 35, and a connecting layer 37 provided to be incontact with the upper surface of the connecting layer 36. Both theconnecting layers 36 and 37 are arranged above the connecting layer 30and are formed of a soft magnetic metal material such as NiFe.

As illustrated in FIG. 3, the write head section 16 is provided with twoconnecting sections 40A and 40B which are embedded in the clad layers 31and 33. The connecting sections 40A and 40B are also formed of a softmagnetic metal material such as NiFe. The connecting sections 40A and40B extend in Z-axis direction so as to connect the connecting layer 30and the connecting layer 36, and are arranged in X-axis direction so asto sandwich the waveguide 32 with a distance.

On the clad layer 33, an insulating layer 38 is provided to fill a spacearound the second layer 352 of the magnetic pole 35. On the insulatinglayer 38, an insulating layer 39 and the coil 41 which is formed inspiral around the connecting layer 37, are stacked in order. The coil 41is intended to generate magnetic flux for recording by flow of a writecurrent, and is formed of a high conductive material such as Cu (copper)and Au (gold). The insulating layers 38 and 39 are configured of aninsulating material such as Al₂O₃, AlN, SiO₂ or DLC. The insulatinglayers 38 and 39 and the coil 41 are covered with an insulating layer42, and an upper yoke layer 43 is further provided to cover theinsulating layer 42. The insulating layer 42 is configured of, forexample, a non-magnetic insulating material flowing on heating, such asa photoresist or a spin on glass (SOG). The insulating layers 38, 39,and 42 are intended to electrically separate the coil 41 from othernearby devices. The upper yoke layer 43 is formed of a soft magneticmaterial with high saturation flux density such as CoFe, the frontportion thereof is connected to the second layer 352 of the magneticpole 35, and a part of the rear portion is connected to the connectinglayer 37. In addition, the front end surface of the upper yoke layer 43is located at a receded position from the ABS 11S.

In the write head section 16 with such a structure, by the write currentflowing through the coil 41, magnetic flux is generated inside amagnetic path which is mainly configured by the leading shield 29, thelower yoke layer 28, the connecting layer 30, the connecting sections40A and 40B, the connecting layers 36 and 37, the upper yoke layer 43,and the magnetic pole 35. Accordingly, a signal magnetic field isgenerated near the end surface of the magnetic pole 35 exposed at theABS 11S, and the signal magnetic field reaches a predetermined region ofthe recording surface 2S (described later) of the magnetic disk 2.

Further, in the magnetic read write head 10, a protective layer 17 madeof Al₂O₃ or the like is formed to cover the entire upper surface of thewrite head section 16.

The light source unit 50 provided at the backward of the magnetic readwrite head 10 includes a laser diode 60 as a light source for emittinglaser light, and a rectangular-solid supporting member 51 supporting thelaser diode 60.

The supporting member 51 is formed of, for example, a ceramic materialsuch as Al₂O₃.TiC. As illustrated in FIG. 4, the supporting member 51 isprovided with an adhesive surface 51A to be adhered to a rear surface11B of the substrate 11, and a light source mounting surface 51Cprovided to be orthogonal to the adhesive surface 51A. The light sourcemounting surface 51C is parallel to the element forming surface 11A. Thelaser diode 60 is mounted on the light source mounting surface 51C. Thesupporting member 51 desirably has a function as a heat sink fordissipating heat generated by the laser diode 60, in addition to afunction to support the laser diode 60.

Laser diodes generally used for communication, for optical disc storage,or for material analysis, for example, InP-based, GaAs-based orGaN-based laser diodes, may be used as the laser diode 60. Thewavelength of the laser light emitted from the laser diode 60 may be anyvalue within the range of 375 nm to 1.7 μm. Specifically, examples ofsuch a laser diode include a laser diode of InGaAsP/InP quaternary mixedcrystal with the emission wavelength region of 1.2 to 1.6 μm. Asillustrated in FIG. 4, the laser diode 60 has a multilayer structureincluding a lower electrode 61, an active layer 62, and an upperelectrode 63. An n-type semiconductor layer 65 including n-type AlGaN isinserted between the lower electrode 61 and the active layer 62, and ap-type semiconductor layer 66 including p-type AlGaN is inserted betweenthe active layer 62 and the upper electrode 63. On each of two cleavagesurfaces of the multilayer structure, a reflecting layer 64 is provided,which totally reflects light to excite oscillation and is formed ofSiO₂, Al₂O₃, or the like. In the reflecting layer 64, an aperture foremitting laser light is provided at a position including an emissioncenter 62A of the active layer 62. The relative position of the lightsource unit 50 and the magnetic read write head 10 is fixed by adheringthe adhesive surface 51A of the supporting member 51 to the rear surface11B of the substrate 11 so that the emission center 62A and the rear endsurface 32A of the waveguide 32 are coincident with each other. Thethickness T_(LA) of the laser diode 60 is, for example, within a rangeof about 60 to 200 μM. A predetermined voltage is applied between thelower electrode 61 and the upper electrode 63 so that laser light isemitted from the emission center 62A of the active layer 62, and is thenincident to the rear end surface 32A of the waveguide 32. The laserlight emitted from the laser diode 60 is preferably polarized light ofTM mode whose electric field oscillates in a direction perpendicular tothe surface of the active layer 62. The laser diode 60 may be drivenwith use of a power source in the magnetic disk device. The magneticdisk device generally includes a power source generating a voltage ofabout 2V, for example, and the voltage generated by the power source issufficient to drive the laser diode 60. In addition, the laser diode 60consumes power of about several tens mW, which may be sufficientlycovered by the power source in the magnetic disk device.

Next, referring to FIGS. 6 to 9 in addition to FIG. 5, the structure andthe functions of each of the waveguide 32, the plasmon generator 34, andthe magnetic pole 35 will be described in detail. FIG. 6 is an explodedperspective view illustrating the structure of each of the waveguide 32,the plasmon generator 34, and the magnetic pole 35, and FIG. 7 is aperspective view illustrating shapes and positional relationship of thewaveguide 32 and the plasmon generator 34. FIG. 8 is a sectional viewillustrating the structures and the functions of the waveguide 32, theplasmon generator 34, and the magnetic pole 35, and the section surfaceis orthogonal to the ABS 11S. FIG. 9 is a plane view illustrating themain part of the plasmon generator 34 viewed from the upper side.

As illustrated in FIG. 7, for example, the waveguide 32 includes an endsurface 32B closer to the ABS 11S, an evanescent light generatingsurface 32C as an upper surface, a lower surface 32D, and two sidesurfaces 32E and 32F, besides the rear end surface 32A illustrated inFIG. 4. The evanescent light generating surface 32C generates evanescentlight based on the laser light propagating through the waveguide 32. InFIGS. 6 to 9, although the end surface 32B arranged on the ABS 11S isexemplified, the end surface 32B may be arranged at a position spacedfrom the ABS 11S.

As illustrated in FIG. 7, the plasmon generator 34 has a first portion34A, a second portion 34B, and a third portion 34C in order from the ABS11S side. In FIG. 7, the boundary between the second portion 34B and thethird portion 34C is indicated by a two-dot chain line. The first tothird portions 34A, 34B, and 34C each have a tow-layer structureprovided with an upper layer 34U on a lower layer 34L. The lower layer34L and the upper layer 34U are preferably formed of a materialessentially (substantially) including one or more of Ag (silver), Cu(copper), Au (gold), Al (aluminum), W (tungsten), Si (silicon), Ir(iridium), Mo (molybdenum), Zn (zinc), Ru (ruthenium), Co (cobalt), Ni(nickel), Cr (chromium), Fe (iron), Pd (palladium), Pt (platinum), Rh(rhodium), Sn (tin), Ta (tantalum), Nb (niobium), Diamond, AlN (aluminumnitride), SiC (silicon carbide), SiAlN, and BN (boron nitride).“Essentially (substantially) include” means that the above-describedmaterials are included as a main component, and the other materials maybe included as a sub-component (for example, impurity) as long as thefunction to generate near-field light NF from the ABS 11S, based on thelaser light propagated through the waveguide 32 is exerted. Here, theconstituent materials of the lower layer 34L and the upper layer 34U maybe the same kind or different kinds.

As illustrated in FIG. 5, the first portion 34A has a V-shapedmid-portion C34 including an edge 344 which is projected toward thewaveguide on a section surface parallel to the ABS 11S, and a couple ofwing portions W34 facing to each other with the mid-portion C34 inbetween in the direction across tracks (X-axis direction). The firstportion 34A has a thickness different along X-axis direction (refer toFIG. 5 to FIG. 7). In other words, the first portion 34A has a thicknessdistribution along X-axis direction. Note that the shape of the sectionsurface of the first portion 34A parallel to the ABS 11S is not changedregardless of the distance from the ABS 11S.

A V-shaped groove is provided in the mid-portion C34 of the firstportion 34A. In other words, a pair of sidewalls 34A1 and 34A2 whichrespectively extend in a direction orthogonal to the ABS 11S isconnected with each other at the edge 344 so as to form a V-shape havinga vertex angle α on a section surface parallel to the ABS 11S. Toincrease the generation efficiency of the near-field light, the vertexangle α is desirably within a range of 55° to 90° both inclusive, and60° is particularly desirable. The edge 344 is a boundary portionbetween the pair of the sidewalls 34A1 and 34A2, and extends in Y-axisdirection from a pointed edge 34G exposed at the ABS 11S as a base pointto the second portion 34B. The pointed edge 34G is a portion generatingthe near-field light. The edge 344 faces the evanescent light generatingsurface 32C of the waveguide 32, and the sidewalls 34A1 and 34A2 aretilted so that the relative distance in X-axis direction becomes widerwith increasing distance from the waveguide 32 with the edge 344 being abase point.

In the wing portions W34 of the first portion 34A, a pair of fringes34A3 and 34A4 is provided so that one end of each of the fringes 34A3and 34A4 in X-axis direction is connected to an end portion on theopposite side to the edge 344 of the sidewalls 34A1 and 34A2,respectively. The pair of the fringes 34A3 and 34A4 extends along aplane (XY-plane) orthogonal to the ABS 11S and parallel to X-axisdirection. The sidewalls 34A1 and 34A2 and the fringes 34A3 and 34A4have a front end surface 342 exposed at the ABS 11S (FIG. 6 and FIG. 7).The first portion 34A has a two-layer structure including the lowerlayer 34L and the upper layer 34U. The lower layer 34L has asubstantially uniform thickness over the mid-portion C34 and the coupleof the wing portions W34. On the other hand, the upper layer 34U is notprovided on the pointed edge 34G (edge 344) of the mid-portion C34 andin the vicinity thereof, and is formed in the vicinity of connectingportion with the wing portion W34 of the mid-portion C34. Specifically,the upper layer 34U of the mid-portion C34 has a thickness to beincreased with increasing distance from the pointed edge 34G (edge 344).Thus, the thickness of the sidewalls 34A1 and 34A2 is minimum at thepointed edge 34G (edge 344) as a whole, and are increased withincreasing distance from the pointed edge 34G (edge 344) in X-axisdirection. In addition, the upper layer 34U configuring the fringes 34A3and 34A4 of the wing portions W34 has, for example, a fixed thicknessequivalent to the maximum thickness of the upper layer 34U of thesidewalls 34A1 and 34A2.

As illustrated in FIG. 7, the second portion 34B has a plate-like bottomportion 34B1 facing the evanescent light generating surface 32C, twoplate-like sidewalls 34B2 and 34B3, and fringes 34B4 and 34B5. Thebottom portion 34B1 is configured so that the width in the X-axisdirection is zero at the boundary portion with the first portion 34A,and becomes wider with increasing distance from the ABS 11S. Thesidewalls 34B2 and 34B3 are provided upright, at both end edge of thebottom portion 34B1 in X-axis direction, toward the side opposite to thewaveguide 32. Here, the sidewalls 34B2 and 34B3 are tilted so that therelative distance (a distance in X-axis direction) becomes wider withincreasing distance from the waveguide 32 with the portion connected tothe bottom portion 34B1 being a base point. In addition, the sidewalls34B2 and 34B3 are connected to the sidewalls 34A1 and 34A2 of the firstportion 34A, respectively. Further, the fringes 34B4 and 34B5 areconnected to an end portion opposite to the side of the bottom portion34B1 of the sidewalls 34B2 and 34B3, respectively, and also connected tothe fringes 34A3 and 34A4 of the first portion 34A, respectively.Moreover, in the sidewalls 34B2 and 34B3 and the fringes 34B4 and 34B5,the section surfaces orthogonal to the corresponding extending directionpreferably have the similar shape to that of the section surfaces of thesidewalls 34A1 and 34A2 and the fringes 34A3 and 34A4 of the firstportion 34A, respectively. In other words, the sidewalls 34B2 and 34B3preferably have a portion whose thickness is gradually increased withincreasing distance from the bottom portion 34B1, and the fringes 34B4and 34B5 preferably have a fixed thickness equivalent to the maximumthickness of the sidewalls 34B2 and 3483, respectively.

The third portion 34C includes a bottom portion 34C1, sidewalls 34C2 and34C3, a wall 34C4, and fringes 34C5, 34C6, and 34C7. The bottom portion34C1 is provided so as to extend continuously from the bottom portion34B1 of the second portion 34B in XY-plane. The sidewalls 34C2 and 34C3are respectively connected to the sidewalls 34B2 and 34B3 of the secondportion 34B, and extend to be orthogonal to the ABS 11S. The sidewalls34C2 and 34C3 are tilted so that the relative distance (the distance inX-axis direction) becomes wider with increasing distance from thewaveguide 32, with the connecting portion to the bottom portion 34C1being a base point. The wall 34C4 couples the bottom portion 34C1 andthe rear end of each of the sidewalls 34C2 and 34C3. The fringes 34C5and 34C6 are respectively coupled to the fringes 34B4 and 34B5 of thesecond portion 34B, and extend to be orthogonal to the ABS 11S. Thefringe 34C7 couples the fringes 34C5 and 34C6 and the rear end of thewall 34C4. The section surface of each of the sidewalls 34C2 and 34C3and the fringes 34C5 and 34C6, which is orthogonal to the correspondingextending direction, preferably have the similar shape to that of thesection surface of each of the sidewalls 34A1 and 34A2 and the fringes34A3 and 34A4 of the first portion 34A, for example. In other words, thesidewalls 34C2 and 34C3 have a portion which is gradually increased inthickness with increasing distance from the bottom portion 34C1, and thefringes 34C5 and 34C6 have a fixed thickness equivalent to the maximumthickness of the sidewalls 34C2 and 34C3, respectively. Note that thewall 34C4 and the fringe 34C7 may not be provided.

As illustrated in FIG. 6 and FIG. 7, the first portion 34A, the secondportion 34B, and the third portion 34C form a space inside thereof forcontaining the first layer 351 of the magnetic pole 35.

The surfaces of the bottom portions 34B1 and 34C1 facing the evanescentlight generating surface 32C of the waveguide 32 with a predetermineddistance are a first surface 341B and a second surface 341C which form asurface plasmon exciting surface 341 as illustrated in FIG. 6. In FIG.6, the boundary between the first surface 341B and the second surface341C is indicated by a two-dot chain line.

The magnetic pole 35 has an end surface 35T exposed at the ABS 11S asillustrated in FIG. 5 and FIG. 6. The end surface 35T includes an endsurface 351T exposed at the ABS 11S in the first layer 351, and an endsurface 352T exposed at the ABS 11S in the second layer 352.

The first layer 351 of the magnetic pole 35 is contained in a spaceformed by the first portion 34A, the second portion 34B, and the thirdportion 34C of the plasmon generator 34. Specifically, the first layer351 has a first portion 351A occupying a space formed by the firstportion 34A, a second portion 351B occupying a space formed by thesecond portion 34B, and a third portion 351C occupying a space formed bythe third portion 34C. The first portion 351A has a triangular prismshape closely contacting the sidewalls 34A1 and 34A2 of the firstportion 34A of the plasmon generator 34, and the area of the sectionsurface parallel to the ABS 11S is constant. In X-axis direction, thewidth of the first portion 351A is desirably smaller than that of themid-portion C34 of the first portion 34A. This is because the maximumintensity of the recording magnetic field from the magnetic pole 35 isincreased. The end surface 351T of the first portion 351A has a pointededge 35C located at a vertex opposite to the second layer 352.

The second portion 351B is closely contacted with the sidewalls 34B2 and34B3 and the bottom portion 34B1 of the second portion 34B of theplasmon generator 34. The width of the second portion 351B in X-axisdirection becomes wider with increasing the distance from the ABS 11S,and becomes wider in Z-axis direction with increasing the distance fromthe waveguide 32. The third portion 351C is closely contacted with thesidewalls 34C2 and 34C3 and the bottom portion 34C1 of the third portion34C of the plasmon generator 34. The width of the third portion 351C inX-axis direction is constant in Y-axis direction, and becomes wider inZ-axis direction with increasing the distance from the waveguide 32.

As illustrated in FIG. 8, in the clad layer 33, a portion disposedbetween the evanescent light generating surface 32C and the surfaceplasmon exciting surface 341 is a buffer portion 33A. In the clad layer33, a portion located backward of the plasmon generator 34 and the firstlayer 351 is a rear portion 33B.

FIG. 9 is a plane view illustrating a positional relationship betweenthe surface plasmon exciting surface 341 and the evanescent lightgenerating surface 32C, and illustrates the plasmon generator 34 and thewaveguide 32 viewed from the magnetic pole 35 side. However, as for theplasmon generator 34, only a surface facing the evanescent lightgenerating surface 32C is illustrated, and the other surfaces areomitted in illustration. As illustrated in FIG. 9, the width of thefirst surface 341B in X-axis direction becomes smaller toward the ABS11S. The first surface 341B has a front end portion 341A3 at a positionwhere end edges 341B1 and 341B2 in X-axis direction intersect with eachother. Angles formed by the end edges 341B1 and 341B2 with respect to adirection (Y-axis direction) perpendicular to the ABS 11S are equal toeach other. Hereinafter, the angle is represented by θ. The angle θ iswithin a range of 3 to 50 degrees, for example, and in particular,preferably within a range of 10 to 25 degrees.

[Method of Manufacturing Magnetic Read Write Head]

In addition to FIG. 4, referring to FIGS. 10 to 16, the method ofmanufacturing the magnetic read write head 10 will be described. FIGS.10 to 16 are for describing forming processes of a main part of themagnetic read write head 10, and illustrate the sectional configurationof the position to be the ABS 11S eventually. In the followingdescription, first, outline of the entire manufacturing processes willbe described with reference to FIG. 4, and then the forming processes ofthe main part (the plasmon generator 34, the magnetic pole 35, and aheat sink 44) will be described with reference to FIGS. 10 to 16. Atthis time, since the detail of the constituent materials and shapes ofthe components has already been described, the description thereof isappropriately omitted.

The magnetic read write head 10 is manufactured mainly by sequentiallyforming and stacking the components by using an existing thin filmprocess. The existing thin film process includes, for example, filmforming technique such as electrolytic plating and sputtering,patterning technique such as photolithography, etching technique such asdry etching and wet etching, and polishing technique such as chemicalmechanical polishing (CMP).

First, the insulating layer 13 is formed on the substrate 11. Next, thelower shield layer 21, the MR element 22 and the insulating layer 24,and the upper shield layer 23 are stacked and formed in this order onthe insulating layer 13 to form the read head section 14. Then, theinsulating layer 25, the intermediate shield layer 26, and theinsulating layer 27 are stacked in order on the read head section 14.

After that, the lower yoke layer 28, the leading shield 29 and theconnecting layer 30, the clad layer 31, the waveguide 32, the clad layer33, the plasmon generator 34, the magnetic pole 35, and the connectinglayers 36 and 37 are formed in order on the insulating layer 27. Notethat the formation of the leading shield 29 may be omitted. Further, byperforming a planarization treatment after the insulating layer 38 isformed to cover the entire surface, the upper surfaces of the magneticpole 35, the insulating layer 38, and the connecting layer 37 areplanarized. Subsequently, the coil 41 embedded by the insulating layers39 and 42 is formed. Moreover, the upper yoke layer 43 connected withthe magnetic pole 35 and the connecting layer 37 is formed to completethe write head section 16. After that, the protective layer 17 is formedon the write head section 16, and by using CMP, the side surface of thestacked structure from the substrate 11 to the protective layer 17 istotally polished to form the ABS 11S. As a result, the magnetic readwrite head 10 is completed.

When the main part of the magnetic read write head 10 is formed, asillustrated in FIG. 10, first, a dielectric layer 331 is formed to coverthe waveguide 32 provided on the clad layer 31. The dielectric layer 331is to be a part of the clad layer 33, and is formed of theabove-described predetermined dielectric material. After that, anetching mask 71 made of a photoresist is formed on the dielectric layer331. The etching mask 71 has an aperture 71A with a size slightly largerthan the outer rim of the upper end of the plasmon generator 34 which isformed later.

Next, as illustrated in FIG. 11, a V-shaped groove 331G is formed in thedielectric layer 331 by etching a portion (exposed portion) of thedielectric layer 331 corresponding to the aperture 71A by, for example,reactive ion etching. The groove 331G is formed so that the lower endthereof is reached to the upper surface of the waveguide 32. The groove331G is formed to have a shape slightly larger than the outer shape ofthe plasmon generator 34 which is formed later.

Subsequently, as illustrated in FIG. 12, the etching mask 71 is liftedoff, and then a dielectric layer 332 is formed to cover the entiresurface by, for example, sputtering. The dielectric layer 332 is to be apart of the clad layer 33 later similar to the dielectric layer 331, andis configured by the above-described predetermined dielectric material.After the dielectric layer 332 is formed, an adhesive film 72 is formedby sputtering to cover the dielectric layer 332. The adhesive layer 72is formed of, for example, Ti (titanium) or Ta (tantalum), and has afunction to improve adhesiveness between the clad layer 33 and theplasmon generator 34. The adhesive film 72 has a thickness of about 1nm. The dielectric layer 332 and the adhesive film 72 are formed tocover not only the upper surface of the dielectric layer 331 but alsothe inner surface of the groove 331G. After the adhesive film 72 isformed, the stacked body has a concave section 72G formed to contain theplasmon generator 34 to be formed later.

Next, as illustrated in FIG. 13, a lower layer 34L of the plasmongenerator 34 to be formed later is formed to cover the entire adhesivefilm 72 by, for example, sputtering or ion beam deposition (IBD). Atthis time, the lower layer 34L has a substantially uniform thickness,and includes a V-shaped portion similar to the shape of the groove 331G.Further, as illustrated in FIG. 14, on the V-shaped portion of the lowerlayer 34L, a resist pattern R1 having two layers of a lower layer R11and an upper layer R12 is formed. At this time, the side surface of theupper layer R12 is separated form the lower layer 34L. In addition, thewidth of the lower layer R11 in X-axis direction is narrower than thewidth of the upper layer R12 so that the resist pattern R1 may have anundercut. Note that as for the resist pattern R1, the lower layer R11may be formed of, for example, polymethylglutarimide (PMGI), and theupper layer R12 may be formed of, for example, a chemically amplifiedpositive resist. After that, the resist pattern R1 is used as a mask toselectively form the upper layer 34U on the lower layer 34L by, forexample, sputtering or ion beam deposition (IBD).

Subsequently, as illustrated in FIG. 15, patterning is performed on theupper layer 34U and the lower layer 34L after the resist pattern R1 isremoved. As a result, the plasmon generator 34 with a first portion 34Aincluding the mid-portion C34 and the wing portions W34, is formed in apredetermined shape.

Finally, as illustrated in FIG. 16, for example, by plating, themagnetic pole 35 is formed to fill the V-shaped groove of (the firstportion of) the plasmon generator 34. The magnetic pole 35 is preferablyformed to have a width in X-axis direction narrower than the width ofthe mid-portion C34 of the first portion 34A. Consequently, the mainpart of the magnetic read write head 10 is completed.

[Control Circuit of Magnetic Disk Device]

Referring to FIG. 17, the circuit configuration of the control circuitof the magnetic disk device illustrated in FIG. 1 and the operation ofthe magnetic read write head 10 are described. The control circuit isprovided with a control LSI (large-scale integrated circuit) 100, a ROM(read only memory) 101 connected to the control LSI 100, a write gate111 connected to the control LSI 100, and a write circuit 112 connectingthe write gate 111 and the coil 41. The control circuit is furtherprovided with a constant current circuit 121 connected to the MR element22 and the control LSI 100, an amplifier 122 connected to the MR element22, and a demodulating circuit 123 connected to an output end of theamplifier 122 and the control LSI 100. The control circuit is furtherprovided with a laser control circuit 131 connected to the laser diode60 and the control LSI 100, and a temperature detector 132 connected tothe control LSI 100.

The control LSI 100 supplies write data and provides a write controlsignal to the write gate 111. Also, the control LSI 100 provides theconstant current circuit 121 and the demodulating circuit 123 with aread control signal, and receives read data output from the demodulatingcircuit 123. In addition, the control LSI 100 provides the laser controlcircuit 131 with a laser ON/OFF signal and an operation current controlsignal.

The temperature detector 132 detects the temperature of the magneticrecording layer of the magnetic disk 2 to transmit temperatureinformation to the control LSI 100.

The ROM 101 stores a control table and the like to control an operationcurrent value which is supplied to the laser diode 60.

During the write operation, the control LSI 100 supplies the write gate111 with the write data. The write gate 111 supplies the write data tothe write circuit 112 only when the write control signal indicates thewrite operation. The write circuit 112 allows a write current to flowthrough the coil 41, based on the write data. As a result, the recordingmagnetic field is generated by the magnetic pole 35, and data isrecorded in the magnetic recording layer of the magnetic disk 2 by thisrecording magnetic field.

During the read operation, the constant current circuit 121 supplies theMR element 22 with a constant sense current only when the read controlsignal indicates the read operation. An output voltage of the MR element22 is amplified by the amplifier 122, and input to the demodulatingcircuit 123. When the read control signal indicates the read operation,the demodulating circuit 123 demodulates the output of the amplifier 122to generate read data which is provided to the control LSI 100.

The laser control circuit 131 controls supply of the operation currentto the laser diode 60, based on the laser ON/OFF signal, and controls avalue of the operation current supplied to the laser diode 60, based onthe operation current control signal. When the laser ON/OFF signalindicates ON operation, the operation current equal to or larger than anoscillation threshold value is supplied to the laser diode 60 by controlof the laser control circuit 131. Therefore, laser light is emitted fromthe laser diode 60, and the emitted laser light propagates through thewaveguide 32. Then, the near-field light NF (described later) isgenerated from the pointed edge 34G of the plasmon generator 34 to heata part of the magnetic recording layer of the magnetic disk 2, and thecoercivity of the part is accordingly lowered. At the time of recording,the part of the magnetic recording layer in which the coercivity islowered is applied with the recording magnetic field generated by themagnetic pole 35. Thus, the recording of the data is performed.

The control LSI 100 determines the value of the operation current of thelaser diode 60 with reference to a control table stored in the ROM 101,based on the temperature and the like of the magnetic recording layer ofthe magnetic disk 2, the temperature being determined by the temperaturedetector 132, and the control LSI 100 controls the laser control circuit131 with use of the operation current control signal so that theoperation current with the determined value is supplied to the laserdiode 60. The control table includes, for example, the oscillationthreshold value and data representing temperature dependence of lightoutput-operation current property of the laser diode 60. The controltable further may include data representing relationship between theoperation current value and the increase amount of the temperature inthe magnetic recording layer heated by the near-field light NF, or datarepresenting temperature dependence of the coercivity in the magneticrecording layer.

The control circuit illustrated in FIG. 17 includes a signal system forcontrolling the laser diode 60, namely, a signal system including thelaser ON/OFF signal and the operation current control signal,independent of the control signal system of the write/read operation.Therefore, the control circuit may achieve not only the electricconduction to the laser diode 60 simply linked with the recordingoperation, but also the electric conduction to the laser diode 60 ofvarious modes. Note that the configuration of the control circuit of themagnetic disk device is not limited to that illustrated in FIG. 17.

Referring to FIG. 8 and FIG. 18, the principal of the near-field lightgeneration and the principal of the heat-assisted magnetic recordingwith use of the near-field light according to the embodiment aredescribed. FIG. 18 is, similar to FIG. 9, a plane view illustrating thepositional relationship between the surface plasmon exciting surface 341and the evanescent light generating surface 32C, and illustrates theplasmon generator 34 and the waveguide 32 viewed from the magnetic pole35 side.

Laser light 45 emitted from the laser diode 60 propagates through thewaveguide 32 to reach the vicinity of the plasmon generator 34. Thelaser light 45 is totally reflected by the evanescent light generatingsurface 32C that is an interface between the waveguide 32 and the buffersection 33A, and accordingly, evanescent light 46 (FIG. 8) leaking intothe buffer section 33A is generated. After that, a surface plasmonpolariton mode is induced by coupling the evanescent light 46 withcharge fluctuation on the surface plasmon exciting surface 341 out ofthe outer surface of the plasmon generator 34. As a result, surfaceplasmons 47 (FIG. 18) are excited on the surface plasmon excitingsurface 341. The surface plasmons 47 propagate on the surface plasmonexciting surface 341 toward the pointed edge 34G. The first surface 341Aof the surface plasmon exciting surface 341 is configured so that thewidth thereof in X-axis direction becomes narrower toward the ABS 11S asdescribed above. Accordingly, when propagating on the first surface341A, the surface plasmons 47 are gradually converted into edge plasmons48 (FIG. 18) as surface plasmons propagating along the edge rims 341A1and 341A2, and the electric field intensity of the plasmons includingthe surface plasmons 47 and the edge plasmons 48 is increased. Thesurface plasmons 47 and the edge plasmons 48 are converted into edgeplasmons 49 (FIG. 18) when reaching the edge 344, and the edge plasmons49 propagate along the edge 344 toward the ABS 11S. The edge plasmons 49eventually reach the pointed edge 34G. As a result, the edge plasmons 49are collected at the pointed edge 34G to generate near-field light NFfrom the pointed edge 34G, based on the edge plasmons 49. The near-fieldlight NF is irradiated toward the magnetic disk 2 and reaches thesurface of the magnetic disk 2 to heat a part of the magnetic recordinglayer of the magnetic disk 2. As a result, the coercivity at the heatedpart of the magnetic recording layer is lowered. In the heat-assistedmagnetic recording, with respect to the part of the magnetic recordinglayer with the coercivity thus lowered, data recording is performed byapplication of the recording magnetic filed generated by the magneticpole 35.

It is considered that the following first and second principals lead tothe increase of the electric field intensity of the plasmons on thefirst surface 341A. First, the description is made for the firstprinciple. In the embodiment, on the metal surface of the surfaceplasmon exciting surface 341, the surface plasmons 47 are excited by theevanescent light 46 generated from the evanescent light generatingsurface 32C. The surface plasmons 47 propagate on the surface plasmonexciting surface 341 toward the pointed edge 34G. The wave number of thesurface plasmons 47 propagating on the first surface 341A is graduallyincreased with decreasing the width of the first surface 341A in X-axisdirection, that is, toward the ABS 11S. As the wave number of thesurface plasmons 47 is increased, the propagating speed of the surfaceplasmons 47 becomes slower. As a result, the energy density of thesurface plasmons 47 is increased to increase the electric fieldintensity of the surface plasmons 47.

Next, the description is made for the second principle. When the surfaceplasmons 47 propagate on the surface plasmon exciting surface 341 towardthe pointed edge 34G, a part of the surface plasmons 47 collide with theedge rims 341A1 and 341A2 of the first surface 341A and is scattered,and accordingly a plurality of plasmons with different wave number aregenerated. A part of the plurality of the plasmons thus generated isconverted into the edge plasmons 48 whose wave number is larger thanthat of the surface plasmons propagating on the plane. In such a way,the surface plasmons 47 are gradually converted into the edge plasmons48 propagating along the edge rims 341A1 and 341A2, and accordingly, theelectric field intensity of the edge plasmons 48 is gradually increased.In addition, the edge plasmons 48 have a larger wave number and slowerpropagating speed compared with the surface plasmons propagating on theplane. Therefore, the surface plasmons 47 are converted into the edgeplasmons 48 to increase the energy density of the plasmons. Further, onthe first surface 341A, the surface plasmons 47 are converted into theedge plasmons 48 as described above, and new surface plasmons 47 arealso generated based on the evanescent light 46 emitted from theevanescent light generating surface 32C. The new surface plasmons 47 arealso converted into the edge plasmons 48. In this way, the electricfield intensity of the edge plasmons 48 is increased. The edge plasmons48 are converted into the edge plasmons 49 propagating through the edge344. Therefore, the edge plasmons 49 are obtainable which have theincreased electric field intensity compared with the surface plasmons 47at the beginning of generation.

In the embodiment, on the first surface 341A, the surface plasmons 47propagating on the plane coexist with the edge plasmons 48 whose wavenumber is larger than that of the surface plasmons 47. It is consideredthat, on the first surface 341A, the increase of the electric fieldintensity of both the surface plasmons 47 and the edge plasmons 48occurs due to the first and second principals described above.Accordingly, in the embodiment, compared with a case where one of thefirst and second principals is effective, the electric field intensityof the plasmons may be further increased.

[Effects of Magnetic Read Write Head and Magnetic Disk Device]

In the embodiment, as described above, the first portion 34A of theplasmon generator 34 having the front end surface 342 which is exposedat the ABS 11S has a minimum thickness at a portion including pointededge 34G which is positioned close to the waveguide 32. Therefore, themagnetic pole 35 and the pointed edge 34G are closely located on the ABS11S. On the other hand, on the first portion 34A, the thickness of apart apart from the pointed edge 34G is increased to improve theefficiency of heat dissipation. Accordingly, compared with a case wherethe first portion 34A has an uniform thickness, while the efficiency andprecision of the heat-assisted magnetic recording are improved, theincrease of temperature in the magnetic pole 35 and in the vicinitythereof are suppressed. In addition, occurrence of corrosion of themagnetic pole 35 and of defect of the structure in the vicinity of themagnetic pole 35 may be prevented. As a result, while securing thelong-time reliability, the recording operation may be achieved withincreased efficiency and stability.

Further, in the embodiment, the magnetic pole 35 is in contact with themid-portion C34 of the plasmon generator 34, and in X-axis direction,the magnetic pole 35 has a width smaller than that of the waveguide 32and of the mid-portion C34. With such a configuration, the recordingmagnetic field generated from the magnetic pole 35 may have adistribution with steeper shape. As a result, the maximum intensity ofthe recording magnetic field necessary for information recording may befurther increased. Further, the mid-portion C34 has a minimum thicknessat the pointed edge 34G, and in X-axis direction, the thickness isincreased with increasing distance from the pointed edge 34G. With sucha configuration, the maximum intensity of the recording magnetic fieldgenerated from the magnetic pole 35 may be further increased. Inaddition, the interface between the magnetic pole 35 and the firstportion 34A is a smooth curved-surface, and therefore the magnetic fluxis prevented from leaking into adjacent tracks.

EXAMPLES Examples of the embodiment of the invention are described indetail. Example 1

In Example 1, the magnetic read write head 10 as the above-describedembodiment illustrated in FIGS. 2 to 7 and the like was manufacturedaccording to the manufacturing method described in the above-describedembodiment. Here, the dimensional ratio of the components in the ABS 11Swere as follows. When the width of the waveguide 32 in X-axis directionwas 1 (500 nm), the width of each of the mid-portion C34 and the wingportion W34 of the first portion 34A was 0.7 and 18, the thickness ofthe lower layer 34L was 0.1, the maximum thickness of the upper layer34U was 0.4, the maximum width of the magnetic pole 35 was 0.7, thethickness of the magnetic pole 35 was 2, and the distance between thepointed edge 34G and the waveguide 32 in Z-axis direction was 0.07(refer to FIG. 5).

Example 2

In Example 2, except that having a sectional surface shape illustratedin FIG. 19, the magnetic read write head 10A having the same structureas that of Example 1 was manufactured according to the manufacturingmethod described in the above-described embodiment. Specifically, in themagnetic read write head 10A, the plasmon generator 34 was configured byonly a portion corresponding to the lower layer 34L in the magnetic readwrite head 10A, and the width of the second layer 352 of the magneticpole 35 was larger than that of the waveguide 32. More specifically,when the width of the waveguide 32 was 1 (500 nm), the width of thesecond layer 352 of the magnetic pole 35 was 2. Therefore, the secondlayer 352 of the magnetic pole 35 was formed to cover also a part of thewing portions W34 of the plasmon generator 34, and the bending portion34 BN is formed at the interface between the plasmon generator 34 andthe magnetic pole 35. In addition, the relative angle θ at theintersection 34J between the side surface of the second layer 352 andthe surface of the plasmon generator 34 was 90°.

Example 3

In Example 3, except that having a sectional surface shape illustratedin FIG. 20, the magnetic read write head 10B having the same structureas that of Example 1 was manufactured according to the manufacturingmethod described in the above-described embodiment. Specifically, in themagnetic read write head 10B, the plasmon generator 34 was configured byonly a portion corresponding to the lower layer 34L in the magnetic readwrite head 10A.

The magnetic read write heads 10, 10A, and 10B of Examples 1 to 3 thusmanufactured were used to perform heat-assisted magnetic recording intoa magnetic disk, and the intensity distribution of the recordingmagnetic field applied to the magnetic disk at that time was examined.The results are illustrated in FIG. 21 and FIG. 22.

FIGS. 21A to 21C correspond to the magnetic read write head 10, 10A, and10B of Examples 1 to 3, respectively, and each illustrate the intensitydistribution of the recording magnetic field applied to the surface ofthe magnetic disk in the direction across write tracks (X-axisdirection). In FIGS. 21A to 21C, the horizontal axis indicates aposition in the direction across write tracks (with the pointed edge 34Gbeing 0 point), and the horizontal axis indicates relative intensity ofthe recording magnetic field (with the maximum peak intensity of Example1 being 1).

Moreover, FIG. 22 illustrates intensity distribution of the recordingmagnetic field applied to the surface of the magnetic disk in a sectionsurface including the pointed edge 34G along a write track direction(Z-axis direction). In FIG. 22, the horizontal axis indicates a positionin the write track direction (with the pointed edge 34G being 0 point),and the vertical axis indicates relative intensity of the recordingmagnetic field (with the maximum peak intensity of Example 1 being 1).Curbed lines C1 to C3 in FIG. 22 correspond to Examples 1 to 3,respectively.

As is obvious from the results in FIG. 21 and FIG. 22, the recordingmagnetic field exhibited the highest maximum intensity in Example 1, andexhibited the lowest maximum intensity in Example 2. In addition, inFIG. 21A to 21C, although undesirable edge peaks EP of the intensity ofthe recording magnetic field were generated at positions correspondingto the intersections 34J in all Examples, the height of the edge peaksEP was allowed to be lowest in Example 1. This was caused that, inExample 1, the plasmon generator 34 had a two-layer structure includingthe lower layer 34L and the upper layer 34U, and the thickness of theplasmon generator 34 was increased at a position away from the pointededge 34G. In other words, it is considered that since the first layer351 of the magnetic pole 35 had a sharper shape, and the angle θ betweenthe side surface of the second layer 352 and the side surface of thefirst layer 351 was increased, the leakage of the magnetic flux from theintersection 3J was reduced (refer to FIG. 5).

Further, in Examples 1 to 3 described above, at the time of performingthe heat-assisted magnetic recording, corrosion and transformation didnot occur in the magnetic pole 35, the clad layer 33, and the like.

From the results of Examples 1 to 3, it was confirmed that theheat-assisted magnetic recording was achievable with higher efficiencyand stability by providing distribution to the thickness of a plasmongenerator as in Example 1.

Although the present invention has been described with the embodiment,the present invention is not limited to the embodiment described above,and various modifications may be made. For example, in the embodiment,although exemplified is a CPP-type GMR element as a read element, theread element is not limited thereto and may be a CIP (current inplane)—GMR element. In this case, an insulating layer needs to beprovided between an MR element and a lower shield layer, and between theMR element and an upper shield layer, and a pair of leads for supplyinga sense current to the MR element needs to be inserted into theinsulating layer. Alternatively, a TMR (tunneling magnetoresistance)element with a tunnel junction film may be used as a read element.

In the embodiment as described above, although the magnetic pole has awidth narrower than that of the V-shaped mid-portion of the plasmongenerator, the present invention is not limited thereto. For example, asthe magnetic read write head 10C illustrated in FIG. 23, the width ofthe second layer 352 of the magnetic pole 35 may be larger than that ofthe waveguide 32. Even in such a case, since performance of the heatdissipation is improved compared with a case where the plasmon generatorhas a uniform thickness, recording operation with stability isachievable for a long time.

Furthermore, in the above-described embodiment, when the upper layer ofthe plasmon generator is manufactured, a lift-off method which uses aresist pattern of two layers as a mask is employed. However, the presentinvention is not limited thereto. For example, a lift-off method whichuses a suspension bridge configured of a hollow beam as a mask may beemployed. In addition, without using a mask such as resist pattern,sputtering may be performed directly on the lower layer from apredetermined angle.

The correspondence relationship between the reference numerals and thecomponents of the embodiment is collectively illustrated here. 1 . . .housing, 2 . . . magnetic disk, 3 . . . head arm assembly (HAA), 4 . . .head gimbals assembly (HGA), 4A . . . slider, 4B . . . suspension, 5 . .. arm, 6 . . . drive section, 7 . . . fixed shaft, 8 . . . bearing, 9 .. . spindle motor, 10 . . . magnetic read write head, 11 . . .substrate, 11A . . . element forming surface, 11S . . . air bearingsurface (ABS), 13 . . . insulating layer, 14 . . . read head section, 16. . . write head section, 17 . . . protective layer, 21 . . . lowershield layer, 22 . . . MR element, 23 . . . upper shield layer, 24, 25,27, 38, 39, 42 . . . insulating layers, 28 . . . lower yoke layer, 29 .. . leading shield, 30, 36, 37 . . . connecting layers, 31, 33 . . .clad layers, 32 . . . waveguide, 34 . . . plasmon generator, C34 . . .mid-portion, W34 . . . wing portion, 34A to 34C . . . first to thirdportions, 34G . . . pointed edge, 34L . . . lower layer, 34U . . . upperlayer, 341 . . . surface plasmon exciting surface, 344 . . . edge, 35 .. . magnetic pole, 351 . . . first layer, 352 . . . second layer, 40A,40B . . . connecting sections, 41 . . . coil, 43 . . . upper yoke layer,45 . . . laser light, 46 . . . evanescent light, 47 . . . surfaceplasmon, 48, 49 . . . edge plasmons, 50 . . . light source unit, 51 . .. supporting member, 60 . . . laser diode, 61 . . . lower electrode, 62. . . active layer, 63 . . . upper electrode, 64 . . . reflecting layer,65 . . . n-type semiconductor layer, 66 . . . p-type semiconductorlayer, NF . . . near-field light.

1. A heat-assisted magnetic write head comprising: a magnetic polehaving an end surface exposed at an air bearing surface; a waveguideextending toward the air bearing surface to propagate light; and aplasmon generator provided between the magnetic pole and the waveguide,and generating near-field light from the air bearing surface, based onthe light propagated through the waveguide; wherein the plasmongenerator has an end portion exposed at the air bearing surface orlocated in close proximity to the air bearing surface, the end portionhaving a minimum thickness in a region close to the waveguide.
 2. Theheat-assisted magnetic write head according to claim 1, wherein the endportion of the plasmon generator has a V-shaped mid-portion including apointed edge projected toward the waveguide, and has a couple of wingportions disposed with the mid-portion in between in a direction acrosswrite tracks.
 3. The heat-assisted magnetic write head according toclaim 2, wherein the magnetic pole is in contact with the mid-portion ofthe plasmon generator.
 4. The heat-assisted magnetic write headaccording to claim 3, wherein thickness of the mid-portion is minimal ina region including the pointed edge, and increases along with increasingdistance from the pointed edge in the direction across write tracks. 5.The heat-assisted magnetic write head according to claim 4, wherein theend surface of the magnetic pole has a width smaller than that of themid-portion in the direction across write tracks.
 6. The heat-assistedmagnetic write head according to claim 1, wherein the plasmon generatorincludes one or more selected from a group consisting of Ag (silver), Cu(copper), Au (gold), Al (aluminum), W (tungsten), Si (silicon), Ir(iridium), Mo (molybdenum), Zn (zinc), Ru (ruthenium), Co (cobalt), Ni(nickel), Cr (chromium), Fe (iron), Pt (platinum), Rh (rhodium), Sn(tin), Ta (tantalum), Nb (niobium), Diamond, AlN (aluminum nitride), SiC(silicon carbide), SiAlN, and BN (boron nitride).
 7. A head gimbalsassembly comprising: a magnetic head slider having a side surfaceprovided with the heat-assisted magnetic write head according to claim1; and a suspension having an end portion provided with the magnetichead slider.
 8. A head arm assembly comprising: a magnetic head sliderhaving a side surface provided with the heat-assisted magnetic writehead according to claim 1; a suspension having an end portion providedwith the magnetic head slider; and an arm supporting other end of thesuspension.
 9. A magnetic disk device including a magnetic recordingmedium and a head arm assembly, the head arm assembly comprising: amagnetic head slider having a side surface provided with theheat-assisted magnetic write head according to claim 1; a suspensionhaving an end portion provided with the magnetic head slider; and an armsupporting other end of the suspension.